The present invention relates generally to improvements in floating roofs, and particularly to a floating roof for covering and protecting petroleum and petrochemical liquids stored in storage tanks.
Floating roofs in use heretofore are of the pontoon type and consist of a single thickness of steel plate shaped to provide a liquid-tight membrane covering the surface of the liquid being stored and carrying on the outer edge thereof a pontoon that imparts buoyancy to the deck and the floating roof. The pontoon is of hollow construction and further includes bulkhead plates therein dividing the pontoon into a plurality of liquid-tight compartments. Examples of typical prior floating roofs are shown in U.S. Pat. No. 2,386,022 granted to John H. Wiggins, and U.S. Pat. No. 3,724,704 granted to Norman W. Edwards, et al.
Such structures are economical and structurally adequate for roofs having relatively small diameters. As the roof diameter increases, the structural requirements imposed upon the pontoon due to the weight of the deck in the event of a water load or leakage becomes uneconomical. Additionally, as the size of the deck portion of the floating roof increases, drainage of rain water therefrom becomes virtually impossible because of deck flexibility and built-in constructional buckles and water collecting pockets.